Have you ever turned on location services and noticed your smartphone battery drain in a matter of minutes? People have come up with theories of why that’s happening: maybe you forgot to quit an app that keeps tracking your location, or your phone’s too busy searching for connections to cell towers and satellites. But which is it? Why do smartphone batteries drain so much faster when it’s using GPS?
Here’s what’s really happening when you turn on location services. First, your GPS receiver — a small chip and antennae located inside your smartphone — is always listening to cell towers, which give it a rough estimate of where you are at all times. Without cellular data or Wi-Fi, the GPS receiver guesses your location. “Without Wi-Fi... you just would not be able to download maps to view your position, so you would see a blue dot in the middle of nowhere,” Columbia Engineering associate professor of electrical engineering Harish Krishnaswamy says in an email interview. Think of it as turning on your map when you’re in airplane mode. Maybe your phone can guess what state or city you’re in, but not the exact neighborhood.
Once you activate location services, that’s when your phone starts to listen for satellites — yep, the ones placed into orbit on what’s called a GPS constellation. While the GPS chip in your phone isn’t able to send signals out, it is constantly receiving signals in order to triangulate your exact positioning.
With GPS turned on, your phone can’t enter sleep mode. The GPS chip is constantly listening for satellites, and if you head underground or are in a place that blocks the signal, like under a metal roof or a Costco, the phone will go into random search mode.
“If you go inside a Walmart [which has] metal roofs, the phone will go into high consumption if location services are turned on,” says Robert W. McGwier, research professor of electrical and computer engineering at Virginia Tech. “It dials through all the different satellites looking for a signal.”
If you’re in a poor signal area and your location services are on, that can drain your smartphone battery far more than if you’re in an area with strong signal. Similarly, you can imagine that if you’re traveling fast through a bullet train or in a car, your signal weakens and battery gets drained faster, partly due to the metal roof and partly due to how many nearby satellites your GPS receiver searches through.
A 2016 study by computer engineering professors in the UK and Saudi Arabia found that under a good signal strength, a battery depletes 13 percent while a weak signal could cause the battery to drop up to 38 percent. (The professors used older devices like the Samsung Galaxy Note 3 and the Sony Xperia Z2 for their experiments, but it’s safe to say the concept still holds true.)
Is there a way smartphones could protect their GPS chips from overusing the battery? A lot of this has to do with GPS technology being old. The Global Positioning System was fully launched in 1995 by the US military and, despite advancements to technology, it still moves pretty slowly. It takes about 12 to 30 seconds for your phone’s GPS to receive a transmission from a satellite, but if it needs to receive signals from all nearby satellites, it could take up to 12 minutes, according to numbers stated by Google software engineer Robert Love that were independently verified by The Verge.
“The issue is that the rate of data transmission to and from the satellite is very slow compared to fiber optics,” Virginia Tech associate professor of chemistry Louis Madsen says in a phone interview, “They’re as fast as they can be, but still not as fast as anything cable-based.”
While GPS may be to blame for fast battery depletion, it’s more likely that when you’re using a GPS-dependent app, a combination of high-power activities is happening. Typically when you’re getting directions from a map app, your screen is on. That’s why apps like Google Maps or Apple Maps are capable of significantly depleting your battery, since they require the GPS chip, phone display, and cellular data to be on for downloading maps and traffic information. Similarly, if you’re constantly looking at your Uber or Lyft app and watching your driver move along a map to your pickup location, your phone is doing multiple things at once to drain power.
Still, there are plenty of ways to manage your battery and optimize your settings, including killing off background apps and adjusting your screen’s brightness when appropriate. “Both Apple and Android are massively incentivized to get this right,” says McGwier, “Every month, both of them update their software and every single time, a major portion is dedicated to improving the battery management.” At its latest developer conference, for example, Google announced an “Adaptive Battery” mode for Android 9 Pie that automatically shuts down background apps you’re not using to reduce overall CPU usage.
So contrary to common perception, GPS itself is not entirely to blame for battery drainage. And if you’re someone who uses these apps often and likes to have your phone screen brightness turned up high, there are several quick fixes to help your phone last through the day.
Comments
This article is not particularly accurate. I have never turned off location services on my phone and it always still lasts long. It pulls 40mah or so so on a 4000mah battery that is just 1% per hour. Also it mentions that GPS data is slow, that’s BS too, all the satellite does is transmit a time, and the difference in time from the various satellites allows you to triangulate a position. The GPS chip doesn’t talk back, there is no communication. The most accurate thing in the article is about screen time, map rendering, map downloading sucking up the battery, but it isn’t the GPS.
By Mike Credelle on 08.17.18 1:12pm
And the time to lock is so long because the signal that is trying to be detected is absurdly small, often barely indistinguishable from noise. It’s not a trivial task.
By Mike Credelle on 08.17.18 4:09pm
If Google Maps is killing your battery by downloading map data, then make areas that you frequently visit available offline. I’ve found that this helps a lot.
Also, if I’m using turn-by-turn navigation but not charging, I usually turn my screen off and just listen to the directions. I believe this saves battery in 2 ways. 1) Not powering the screen 2) Not rendering and redrawing the map.
Hope this helps someone!
By cwacht on 08.17.18 3:37pm
"A 2016 study by computer engineering professors in the UK and Saudi Arabia found that under a good signal strength, a battery depletes 13 percent while a weak signal could cause the battery to drop up to 38 percent"
13 percent over what time period? An hour? A second?
By aardWolf on 08.17.18 4:01pm
Legitimate question here: how do the GPS sportwatches like the ones from Garmin work in comparison to a smartphone.
Granted they don’t track your location continuously, but most of the time they rely solely on GPS (or GLONASS, the alternative Russian solution) to pinpoint your location, isn’t it?
If someone knows the answer to that, I’d be very glad to hear it.
By diogonovaes on 08.17.18 4:32pm
They work the same way, the difference there is that they only search for your location when they need to (for example, during workouts, etc), so they rarely draw from the GPS chip.
By phishfi on 08.17.18 5:17pm
You don’t need wifi or cellular to location track, it’s just faster and lower power, but far less accurate, so phones more heavily rely on it to augment GPS slow lock times. In a smartwatch when you turn GPS on, it can take a while to lock and the battery only lasts for like 4 hours, because the battery is much smaller, so it’s only on when you run or otherwise tell it to turn gps on. And I believe they can’t use wifi for location on a smartwatch because even though phones use it, you still have to know where the wifi hotspot is located, which requires a constantly updated database (or a cellular connection)
By Mike Credelle on 08.17.18 5:36pm
Phones use AGPS, where information about the satellite orbits (ephemeris) are downloaded over the Internet instead of from the satellites (20+ seconds according to Wikipedia). It can also have corrections for the current, localized ionospheric conditions.
Not sure if it affects things in practice, but watches have limited space to cram antennas compared to phones. Also, not sure how being attached to your wrist compares to the signal attenuation of holding a phone in your hand or in your pocket.
By eyu on 08.17.18 6:26pm
Modern GPS sportwatches are very battery efficient when the GPS is off. When the GPS is on, battery use depends mostly on how frequently they update the GPS track. On my Suunto Ambit3 Peak (a 2014 model year watch with a big battery), the most accurate track is updated every 1 second, which gives it a 20 hour GPS on battery life. When set to update every 5 seconds, it’s good for 30 hours GPS on. When set to update every 60 seconds, it’s good for 200 hours GPS on.
Depending on the specific model, Garmins will also update as frequently as every 1 second. There’s also a "smart" update mode, I think default and not changeable on the cheaper models, where it will update the GPS more frequently if your track is turning constantly, like on a twisty trail, and less frequently when you are going in a straight line.
GPS sport watches within the past 6 years or so will get satellite orbit information updated when plugged in to download data/charge or are otherwise connected to the internet. That enables them to lock in to a location almost immediately after you turn the GPS on, without using wifi or cellular that they don’t have.
This article is wrong about GPS being the cause of battery drain issues. The study that is cited for 13% vs. 38% battery depletion with strong and weak signals has almost nothing to do with GPS. The phones are using power looking for/trying to connect to weak or undetected cell towers, not weak GPS signals.
By Lightning Racer on 08.17.18 11:38pm
I really want to like this article, but it doesn’t talk about iOS devices. It would have been nice to compare, and ask Apple what they are doing about.
By DeanLubaki on 08.17.18 7:52pm
I’ve had gps battery drainage experience all over the board, even on modern smartphones. From hardly any drain to fast drainage under similar circumstances when traveling between work and home on the same route.
Generally with cellular and gps on, triangulation is quite instant, under 10 seconds mostly. With airplane mode off and gps/location on triangulation can take anywhere from 30 seconds to more than 5 minutes of waiting.
To date accuracy is also also has to be desired with deviations in accuracy ranging between 5-15 meters on best performance days. This is more often an issue for example when you have many smaller roads close to one another or a secondary road close to a highway. The app at junctions thinks you’re taking on the secondary road while you’re in the car on the highway. For offroute navigation it could make the difference to taking a wrong path. Improving the accuracy with up to 2-4 meters would make a world of difference in performance and be a revolutionary experience on modern smartphones.
By w.evenhuis on 08.19.18 6:23am